Gun manufacturers and retailers throughout New England are struggling to keep up with surging demand as buyers, worried their options may soon be limited,
snap up firearms and ammunition.

Shops say they have sold out of many popular gun models, including variations of the AR-15-style rifle used in last month’s mass shootings in Newtown, Conn. Some retailers have resorted to capping the number of bullets customers can buy in an effort to preserve dwindling inventories, or taken to marking up prices.

The sharp increase in sales is fueled by the looming prospect of greater controls on firearms. Proposals to further restrict or regulate ownership are pending nationally and in Massachusetts.

The surge in purchases can be gauged by the wave of background checks required for prospective gun buyers. Nine of the 10 busiest days for background checks ever recorded by the FBI were in the past two months. In December alone, the agency performed 25,251 checks for would-be buyers in Massachusetts — an increase of 73 percent from a year earlier.

“People are afraid of what Obama is going to do,” said Ted Oven, owner of Northeast Trading Co. in North Attleborough. “People who were going to buy in the spring are rushing to buy now.”

On a recent day, the store’s display wall featured only two AR-15-style rifles. Oven said about 60 customers have requested similar guns that have yet to arrive. He also submitted orders for $1 million worth of guns and accessories at a trade show in Connecticut this month, but no one could guarantee a delivery date.

Johnny Donnelly, a firearms instructor from Woburn, said he had to add a second four-hour firearms safety class on Sunday
to accommodate demand from new gun owners.

“It’s definitely the highest interest I’ve ever seen,” said Donnelly, who hopes to open a gun store in Massachusetts this year. “Even people I didn’t know were interested in firearms are talking about it.”

Some gun clubs are also worried about finding enough ammunition for training programs, said Jim Wallace, executive director of the Gun Owners’ Action League in Northborough, the Massachusetts state affiliate of the National Rifle Association.

“Even the wholesalers are pretty much out,” Wallace said. “Firearms sales are up across the board.”

The increase comes at a time when many manufacturers already were having a difficult time producing enough guns and bullets to keep stores fully stocked.

Smith & Wesson Holding Corp. had $332.7 million worth of backlogged orders at the end of October, nearly double its backlog from a year earlier. The Springfield company, which introduced 11 “modern sporting rifle” models — semiautomatic guns like the AR-15 — in fiscal year 2011, recently said it planned to boost production, with both outside vendors and expansion of its own facilities.

Stag Arms, a maker of AR-15-style rifles in New Britain, Conn., reported this month that it has two years of back orders for the guns and related parts. The company said it is not taking new orders and has asked office staff to help with packing and shipping to speed deliveries “before any potential government restriction” on sales is enacted.

Four Seasons Firearms, a Woburn gun seller, said many weapons featured on its website are out of stock. The store said it has ordered hundreds of Smith & Wesson AR-15-style rifles but does not know when they will arrive.

Jonathan Wiggs/Globe staff

Just a few days ago guns were seen on the walls of Northeast Trading Co.

In a note to investors this month, New York investment banking firm Cowen and Co. said retailers are citing “strong demand and very tight/no inventory for tactical rifles and handguns” due to fears about stepped up gun control at the federal and state levels.

In the short run, Cowen analyst Cai Von Rumohr wrote, higher demand is likely to boost profit at Smith & Wesson. But he cautioned that the “overheated” market probably won’t last. Von Rumohr noted gun sales increased before Congress passed an “assault weapons” ban in 1994, only to drop once the now-expired law took effect.

Industry analysts said they expect some added restrictions to come out of the furor over Newtown, though it is unclear which measures, if any, will make it through Congress.

President Obama this month signed nearly two dozen executive orders, many designed to improve background checks, and proposed broader measures that require legislative approval, including prohibitions on so-called assault weapons and magazines that hold more than 10 bullets.

Last week, Democratic US Senator Dianne Feinstein of California filed a bill that would outlaw the sale and manufacture of 157 kinds of guns, including “all AR types.” Smith & Wesson’s entire line of modern sporting rifles — representing a fifth of its 2012 sales — was included on the list.

In Massachusetts, Governor Deval Patrick has proposed limiting residents to one gun purchase a month and barring magazines with room for more than seven bullets.

For gun enthusiasts, the rising demand has not only made it difficult to buy certain new weapons, it has increased the cost of using guns they already own.

Dan Sullivan, 55, of Groton, said ammunition for some popular rifles and handguns has become so pricey that he switched to smaller-caliber rifles, which use less-expensive bullets, for target practice at a shooting range.

Rounds for Sullivan’s AR-15 and his wife’s rifle that used to sell for 35 to 45 cents each are now fetching about $1. That can add up to a couple hundred dollars for an outing with family and friends, he said.

“There’s practically no ammunition on sale at retailers,” Sullivan said. “And if you can find it, it’s two times what you could buy it for normally.”

As for tracking down a few more handguns to round out his collection, Sullivan has searched several stores in recent weeks without luck.